There are several objectives of this research. One is to develop chemical syntheses of certain complex molecules showing antitumor, antiviral or antiobiotic activity of an exceptional sort. In order for such syntheses to be practical and sufficiently flexible to allow the production of a wide range of structural analogs, new synthetic reactions and methodology must be developed. A second goal, therefore, is to discover new synthetic principles and methods, in order to extend our capacity to effect syntheses of the most challenging type. In a most general sense we seek to extend the power of organic synthesis upon which much of the progress of medicine ultimately depends and at the same time to achieve the synthesis of important substances. The proposed research centers around the following biologically active substances or families of substances: 1) maytansines, 2) erythromycins, 3) oleandomycin, 4) aplasmomycin, 5) rifamycins, 6) coriolins, 7) quadrone, 8) ovalicin, 9) interferon inducing substances and 10) cyclic CMP analogs. Finally, it is our aim, through these chemical studies, to make significant contributions to medicine.